Reactive desorption electrospray ionization (DESI) can be used to track reactions that are otherwise difficult to follow by mass spectrometry, according to two reports. In one paper, Richard N. Zare and coworkers at Stanford University describe using DESI-MS to capture and analyze reactive intermediates during the formation of a ruthenium catalyst (Angew. Chem. Int. Ed., DOI: 10.1002/anie.201004861). The researchers deposited the starting ruthenium complex on a surface and incorporated the . . .